Studies have been demonstrating Pfaffia paniculata root (Brazilian ginseng) anticarcinogenic activities. We evaluated its chemopreventive effects on preneoplastic hepatic lesions. BALB/c aged-15 days received 10mug/g of diethylnitrosamine carcinogen, i.p. They were fed with the powdered root added to the diet: 0.5, 2 or 10% during 27 weeks. After being sacrificed, the macroscopic lesions in the livers were examined. Preneoplastic or neoplastic lesions were measured, quantified and classified morphologically. The treatment reduced the incidence, mean area and number of lesions, indicating an inhibitory effect of these roots on hepatocarcinogenesis promotion or progression steps.